1. Field of the Invention
The present invention relates to a wafer supporting plate suitable for supporting a wafer during a semiconductor-forming process; more particularly, the invention relates to a wafer supporting plate capable of sensing the positioning condition of the wafer on the supporting plate during a heat treatment or other semiconductor-forming processes for detecting whether the wafer is being positioned nomally on the supporting plate.
2. Description of the Related Art
At present, semiconductor wafers tend to have larger and larger sizes, wherein the manufacturing techniques for forming wafers have evolved from 6-inch wafers, 8-inch wafers, and now towards the 12-inch wafers. The increases in wafer size means that the manufacturing cost of each wafer also has to be increased to keep up with newer technologies. Therefor, it is inevitable, and not surprisingly, that the semiconductor industry has been working hard on how to reduce the redundancy rate of the wafers handled during the manufacturing procedure as well as to minimize the pollution problem resulted from improper processing of the damaged wafers.
The situation in which the wafers are damaged occurs mostly frequently when the wafers are processed in a wafer storage chamber or a reaction chamber or when the wafers are conveyed to different locations by a carrier. As shown in FIG. 1, a general wafer supporting apparatus for the manufacture of wafers is presented according to a conventional method, wherein the wafer manufacturing system shown comprises a supporting plate 10. In addition, at least three supporting props 15 are provided on the supporting plate 10. The supporting props 15 are typically not arranged in-line; instead, the supporting props 15 are arranged into a n-agon shape, where nxe2x89xa73. For example, FIG. 2A and FIG. 2B illustrate a hexagon arrangement of the supporting props 15 whereby a wafer 20 is placed on the supporting plate 10. Each of the supporting prop surface 11 supports the wafer 20 by contacting the rim, and the wafer forms a plane parallel to the plane formed by the supporting plate.
However, the supporting plate and the automatic manipulator such as a mechanical arm that carry the wafer tend to lose their positioning precision due to the long running period. As a result, the wafer cannot be located to the predetermined positions, and such a dislocated wafer when being processed in a reaction chamber, for example, can not be accepted since an uneven temperature distribution or chemical deposition, erratic exposure, scratching, or sometimes even crashing between the wafers may occur, which can eventually wreck the reaction chamber.
Moreover, the defective wafers typically are not sorted out until a great extent of the manufacturing process has been carried out, which, in other words, means that the operator or engineer who is in charge of handling the process can not be well informed before or during the occurrence of a mishap. As a result, the manufacturing cost has to be increased-while the projected time of delivery is delayed. The above problem is further complicated since the engineer or operator can not trace the exact cause of the problem that produces the faulty wafer, which makes the situation even more difficult and therefore increases the required time for repairing.
To solve the problems described above, an embodiment of the present invention provides a wafer supporting plate comprising a plurality of sensing devices capable of sensing the positioning condition of the wafer on the supporting plate during a heat treatment or other semiconductor-forming processes for judging whether the wafer is being positioned normally on the supporting plate. For example, if the positioning condition of the wafer being processed is detected by the above-mentioned sensing devices to be in a state of abnormality, the process is suspended immediately. This preventive measure, according to the present invention provides a safeguard to the wafers being processed so that none of which can be scratched or even cracked; furthermore, the present invention provides a quick way of tracing the cause of an abnormal positioning of a wafer for shortening the repairing or adjusting time of a machine.
Accordingly, the present invention provides a wafer supporting plate suitable for semiconductor manufacturing, comprising a supporting plate body, at least three supporting props disposed on the supporting plate body for receiving and supporting a wafer, at least three sensing devices each disposed besides the supporting props and within the range encircled by the supporting props on the supporting plate body respectively for detecting whether all of supporting props are supporting the wafer normally or optimally.
In addition, another embodiment of the present invention provides a wafer supporting plate further comprising a logic circuit connected to the sensing devices which can be triggered by the sensing devices to suspend the semiconductor-forming process being performed on the wafer as soon as one of the sensing devices detects an abnormality in the positioning condition of the wafer at the location of the supporting props.